Thermal transport in monolayer zinc-sulfide: effects of length, temperature and vacancy defects.

Of late, atomically thin two-dimensional zinc-sulfide (2D-ZnS) shows great potential for advanced nanodevices and as a substitute to graphene and transition metal di-chalcogenides owing to its exceptional optical and electronic properties. However, the functional performance of nanodevices significantly depends on the effective heat management of the system. In this paper, we explored the thermal transport properties of 2D-ZnS through molecular dynamics simulations. The impact of length, temperature, and vacancy defects on the thermal properties of 2D-ZnS are systematically investigated. We found that the thermal conductivity (TC) rises monotonically with increasing sheet length, and the bulk TC of ∼30.67 W mK-1is explored for an infinite length ZnS. Beyond room temperature (300 K), the TC differs from the usual 1/Trule and displays an abnormal, slowly declining behavior. The point vacancy (PV) shows the largest decrease in TC compared to the bi vacancy (BV) defects. We calculated phonon modes for various lengths, temperatures, and vacancies to elucidate the TC variation. Conversely, quantum corrections are used to avoid phonon modes' icing effects on the TC at low temperatures. The obtained phonon density of states (PDOS) shows a softening and shrinking nature with increasing temperature, which is responsible for the anomaly in the TC at high temperatures. Owing to the increase of vacancy concentration, the PDOS peaks exhibit a decrease for both types of defects. Moreover, the variation of the specific heat capacity and entropy with BV and PV signify our findings of 2D-ZnS TC at diverse concentrations along with the different forms of vacancies. The results elucidated in this study will be a guide for efficient heat management of ZnS-based optoelectronic and nano-electronic devices.

Non-Invasive Identification of Nutrient Components in Grain.

Digital farming is a modern agricultural concept that aims to maximize the crop yield while simultaneously minimizing the environmental impact of farming. Successful implementation of digital farming requires development of sensors to detect and identify diseases and abiotic stresses in plants, as well as to probe the nutrient content of seeds and identify plant varieties. Experimental evidence of the suitability of Raman spectroscopy (RS) for confirmatory diagnostics of plant diseases was previously provided by our team and other research groups. In this study, we investigate the potential use of RS as a label-free, non-invasive and non-destructive analytical technique for the fast and accurate identification of nutrient components in the grains from 15 different rice genotypes. We demonstrate that spectroscopic analysis of intact rice seeds provides the accurate rice variety identification in ~86% of samples. These results suggest that RS can be used for fully automated, fast and accurate identification of seeds nutrient components.

Vacancy-induced thermal transport in two-dimensional silicon carbide: a reverse non-equilibrium molecular dynamics study.

Because of its impressive electrical, thermal, and mechanical properties, two-dimensional silicon carbide (2D-SiC) has recently gained tremendous attention in the field of nanoelectronics and optoelectronics. Here, we investigated the effects of various types of defects such as bi-, point-, and mixed-vacancies on the thermal conductivity of 2D-SiC using reverse non-equilibrium molecular dynamics simulation. The effects of temperature variation on the thermal conductivity of vacancy-defected 2D-SiC were also studied. A significant reduction of the thermal conductivity was observed when the concentrations of the vacancies were increased. The point vacancy resulted in the thermal conductivity decreasing more quickly as compared to bi vacancy and mixed vacancy defects. Moreover, increasing the temperature of vacancy-defected 2D-SiC further reduced the thermal conductivity due to a strong phonon-vacancy scattering effect. Because of the introduction of vacancy defects in the acoustic phonon density of states (PDOS), a softening behavior in the intensity of the characteristic peaks is perceived, and with increasing temperature, a frequency shrinking is noted in the PDOS curves, both of which contribute to the reduction of the thermal conductivity. Additionally, rapid softening of the phonon transmission spectrum and increase in entropy were obtained for the point vacancy-defected structure, which clearly confirms our findings at different vacancy concentrations as well as for types of vacancies. These findings are very much imperative for realizing heat dissipation in nano- and optoelectronic devices based on 2D-SiC as well as for demonstrating an effective method for modulating 2D-SiC thermal conductivity through defect engineering.

Anomalous temperature dependent thermal conductivity of two-dimensional silicon carbide.

Recently, two-dimensional silicon carbide (2D-SiC) has attracted considerable interest due to its exotic electronic and optical properties. Here, we explore the thermal properties of 2D-SiC using reverse non-equilibrium molecular dynamics simulation. At room temperature, a thermal conductivity of ∼313 W mK-1 is obtained for 2D-SiC which is one order higher than that of silicene. Above room temperature, the thermal conductivity deviates the normal 1/T law and shows an anomalous slowly decreasing behavior. To elucidate the variation of thermal conductivity, the phonon modes at different length and temperature are quantified using Fourier transform of the velocity auto-correlation of atoms. The calculated phonon density of states at high temperature shows a shrinking and softening of the peaks, which induces the anomaly in the thermal conductivity. On the other hand, quantum corrections are applied to avoid the freezing effects of phonon modes on the thermal conductivity at low temperature. In addition, the effect of potential on the thermal conductivity calculation is also studied by employing original and optimized Tersoff potentials. These findings provide a means for better understating as well as designing the efficient thermal management of 2D-SiC based electronics and optoelectronics in near future.

Balancing for an Effective Communication in Organizations.

Communication is an essential part of all activities of organizations. However, it is affected by technology. Today, email and social media are popular methods of communication in organizations. Each of the listed methods has advantages and disadvantages which will be discussed in this letter which tries to drive the attention of organizations to the need for a standard and balanced approach toward communication.

Initial Experience with Endoscopic Ultrasound.

Since its introduction in early 1990s, endoscopic ultrasound (EUS) has become integral to the diagnosis and staging of various luminal, extraluminal gastrointestinal (GI) and certain non-GI lesions. There is no data on EUS experience in Bangladesh. The aim of this paper is to evaluate the initial recent experience and clinical impact of EUS. All EUS procedures data were recorded prospectively from July 2013 to December 2014. These included patients' demographics, referral details, provisional diagnosis, management plan before and after EUS & indications of procedures. EUS-FNA data recorded included details regarding site, number of passes and histological diagnosis. Two hundred & four EUS procedures were carried out over one and half years. Male female ratio was 1.4:1, mean age was 46.4 ± 20 years. Of these procedures 148 (72.5%) were referrals from physicians and 56 (27.5%) were from surgeons. Most common indications were pancreatobiliary pathologies, esophageal & gastric pathologies. Pancreatobiliary lesions (n = 165, 80.9%) included patients with (A) Benign pathologies: Microliths in Gall baldder (n = 6), Gall stones (n = 12), Biliary ascarrisis (n = 22), Choledocholithiasis (n = 42), Acute Pancreatitis (n = 9), Chronic Pancreatitis (n = 15), Pancreatic pseudocysts(n = 4) (B) Malignant Pathologies : GB Carcinoma (n = 4), Cholangiocarcinoma (n = 29), Ca- pancreas (n = 9), Periampullary carcinoma (n = 12). Esophageal lesion was 9.3% (n = 19) of total procedures. Forty seven percent (n = 9) of EUS procedures on esophagus were for staging of esophageal malignancy, 10. 5% (n = 2) for restaging or recurrence after chemoradiation and 21% (n = 4) for submucosal lesions. Fifteen EUS procedures were carried out for gastric lesions, seven were for staging of gastric carcinoma, four were for assessment of submucosal lesions (e.g. GIST, lipoma or external compression), 02 for assessment of polyps and two for gastric ulcers.In clinical impact & outcome study, changes in diagnosis, management, avoidance of investigations and usefulness of EUS were evaluated. Diagnosis was changed in 34.4% (64/186) & management was changed in 45%(92/204). Additional investigation was avoided in 57.8% (118/204). This is the first report of Bangladesh experience of EUS to date. EUS is safe, accurate, cost effective & very useful tool for diagnosis and management of G.I. disorders.

Protein folding in HP model on hexagonal lattices with diagonals.

Three dimensional structure prediction of a protein from its amino acid sequence, known as protein folding, is one of the most studied computational problem in bioinformatics and computational biology. Since, this is a hard problem, a number of simplified models have been proposed in literature to capture the essential properties of this problem. In this paper we introduce the hexagonal lattices with diagonals to handle the protein folding problem considering the well researched HP model. We give two approximation algorithms for protein folding on this lattice. Our first algorithm is a 5/3-approximation algorithm, which is based on the strategy of partitioning the entire protein sequence into two pieces. Our next algorithm is also based on partitioning approaches and improves upon the first algorithm.

Clinico-epidemiological Characteristics of the Physician Affected with Covid-19.

Coronavirus disease 2019 (Covid-19) disease have been associated with significant mortality amongst doctors globally including Bangladesh. To delineate the clinico-epidemiological characteristics of the physician affected with Covid-19 was the objective of the study. This cross-sectional 'Facebook' based survey was conducted in the period of August 2020 to September 2020. Snowball sampling methods was followed. A total of 151 physicians affected with Covid-19 participated in this survey. Self-reported perceived severity scale (zero meaning not severe at all and ten denoting the most severe) was used. Collected data were analyzed by SPSS 25.0. Among the participants, the majority were male, 98(64.9%). The most prevalent affected age groups were 24-35 years 131(86.8%). Approximately 45.0% worked in COVID dedicated hospital. Entry-level physicians (Medical Officer or Assistant Surgeon) were the most affected 117(94.4%). One-third of the physicians had at least the one co-morbidity. Bronchial asthma, obesity and diabetes were the most frequent. Predominate symptoms of the infection were fever 94(62.3%), cough 94(62.3%) and myalgia 92(60.9%). Half of the participants had sore throat, anosmia, gastro-intestinal symptoms and one-third of the patients developed dyspnea. Perceived severity of the symptoms ranged between 2 and 6. The pattern of drug use to prevent the Covid-19 showed no uniformity. However, intake of Zinc, Vitamin C, Vitamin D, antihistamine and Ivermectin was found in 74.8%, 67.5%, 41.7%, 49.0% and 37.7% respectively. As the current pandemic continues to evolve, physicians must be equipped with appropriate knowledge, skills and must be cautious on the prevention measures against Covid-19.

Anisotropic crystal orientations dependent mechanical properties and fracture mechanisms in zinc blende ZnTe nanowires.

The orientations of crystal growth significantly affect the operating characteristics of elastic and inelastic deformation in semiconductor nanowires (NWs). This work uses molecular dynamics simulation to extensively investigate the orientation-dependent mechanical properties and fracture mechanisms of zinc blende ZnTe NWs. Three different crystal orientations, including [100], [110], and [111], coupled with temperatures (100 to 600 K) on the fracture stress and elastic modulus, are thoroughly studied. In comparison to the [110] and [100] orientations, the [111]-oriented ZnTe NW exhibits a high fracture stress. The percentage decrease in fracture strength exhibits a pronounced variation with increasing temperature, with the highest magnitude observed in the [100] direction and the lowest magnitude observed in the [110] direction. The elastic modulus dropped by the largest percentage in the [111] direction as compared to the [100] direction. Most notably, the [110]-directed ZnTe NW deforms unusually as the strain rate increases, making it more sensitive to strain rate than other orientations. The strong strain rate sensitivity results from the unusual short-range and long-range order crystals appearing due to dislocation slipping and partial twinning. Moreover, the {111} plane is the principal cleavage plane for all orientations, creating a dislocation slipping mechanism at room temperature. The {100} plane becomes active and acts as another fundamental cleavage plane at increasing temperatures. This in-depth analysis paves the way for advancing efficient and reliable ZnTe NWs-based nanodevices and nanomechanical systems.

Crystal orientation-dependent tensile mechanical behavior and deformation mechanisms of zinc-blende ZnSe nanowires.

Crystal deformation mechanisms and mechanical behaviors in semiconductor nanowires (NWs), in particular ZnSe NWs, exhibit a strong orientation dependence. However, very little is known about tensile deformation mechanisms for different crystal orientations. Here, the dependence of crystal orientations on mechanical properties and deformation mechanisms of zinc-blende ZnSe NWs are explored using molecular dynamics simulations. We find that the fracture strength of [111]-oriented ZnSe NWs shows a higher value than that of [110] and [100]-oriented ZnSe NWs. Square shape ZnSe NWs show greater value in terms of fracture strength and elastic modulus compared to a hexagonal shape at all considered diameters. With increasing temperature, the fracture stress and elastic modulus exhibit a sharp decrease. It is observed that the {111} planes are the deformation planes at lower temperatures for the [100] orientation; conversely, when the temperature is increased, the {100} plane is activated and contributes as the second principal cleavage plane. Most importantly, the [110]-directed ZnSe NWs show the highest strain rate sensitivity compared to the other orientations due to the formation of many different cleavage planes with increasing strain rates. The calculated radial distribution function and potential energy per atom further validates the obtained results. This study is very important for the future development of efficient and reliable ZnSe NWs-based nanodevices and nanomechanical systems.

Benthic macroinvertebrate community shifts based on Bti-induced chironomid reduction also decrease Odonata emergence.

Chironomid larvae (Diptera: Chironomidae) often dominate aquatic macroinvertebrate communities and are a key food source for many aquatic predators, such as dragonfly and damselfly larvae (Odonata). Changes in aquatic macroinvertebrate communities may propagate through terrestrial food webs via altered insect emergence. Bacillus thuringiensis israelensis (Bti)-based larvicides are widely used in mosquito control but can also reduce the abundance of non-biting chironomid larvae. We applied the maximum field rate of Bti used in mosquito control three times to six mesocosms in a replicated floodplain pond mesocosm (FPM) system in spring for two consecutive years, while the remaining six FPMs were untreated. Three weeks after the third Bti application in the first year, we recorded on average a 41% reduction of chironomid larvae in Bti-treated FPMs compared to untreated FPMs and a shift in benthic macroinvertebrate community composition driven by the reduced number of chironomid, Libellulidae and Coenagrionidae larvae (Odonata). Additionally, the number of emerging Libellulidae (estimated by sampling of exuviae in the second year) was reduced by 54% in Bti-treated FPMs. Since Odonata larvae are not directly susceptible to Bti, our results suggest indirect effects due to reduced prey availability (i.e., chironomid larvae) or increased intraguild predation. As Libellulidae include species of conservation concern, the necessity of Bti applications to their habitats, e.g. floodplains, should be carefully evaluated.

Finite mixture Negative Binomial-Lindley for modeling heterogeneous crash data with many zero observations.

Crash data are often highly dispersed; it may also include a large amount of zero observations or have a long tail. The traditional Negative Binomial (NB) model cannot model these data properly. To overcome this issue, the Negative Binomial-Lindley (NB-L) model has been proposed as an alternative to the NB to analyze data with these characteristics. Research studies have shown that the NB-L model provides a superior performance compared to the NB when data include numerous zero observations or have a long tail. In addition, crash data are often collected from sites with different spatial or temporal characteristics. Therefore, it is not unusual to assume that crash data are drawn from multiple subpopulations. Finite mixture models are powerful tools that can be used to account for underlying subpopulations and capture the population heterogeneity. This research documents the derivations and characteristics of the Finite mixture NB-L model (FMNB-L) to analyze data generated from heterogeneous subpopulations with many zero observations and a long tail. We demonstrated the application of the model to identify subpopulations with a simulation study. We then used the FMNB-L model to estimate statistical models for Texas four-lane freeway crashes. These data have unique characteristics; it is highly dispersed, have many locations with very large number of crashes, as well as significant number of locations with zero crash. We used multiple goodness-of-fit metrics to compare the FMNB-L model with the NB, NB-L, and the finite mixture NB models. The FMNB-L identified two subpopulations in datasets. The results show a significantly better fit by the FMNB-L compared to other analyzed models.

Tensile Mechanical Behavior and the Fracture Mechanism in Monolayer Group-III Nitrides XN (X= Ga, In): Effect of Temperature and Point Vacancies.

In this study, we have thoroughly investigated the tensile mechanical behavior of monolayer XN (X = Ga, In) using molecular dynamics simulations. The effects of temperature (100 to 800 K) and point vacancies (PVs, 0.1 to 1%) on fracture stress, strain, and elastic modulus of GaN and InN are studied. The effects of edge chiralities on the tensile mechanical behavior of monolayer XN are also explored. We find that the elastic modulus, tensile strength, and fracture strain reduce with increasing temperature. The point defects cause the stress to be condensed in the vicinity of the vacancies, resulting in straightforward damage. On the other hand, all the mechanical behaviors such as fracture stress, elastic modulus, and fracture strain show substantial anisotropic nature in these materials. To explain the influence of temperature and PVs, the radial distribution function (RDF) at diverse temperatures and potential energy/atom at different vacancy concentrations are calculated. The intensity of the RDF peaks decreases with increasing temperature, and the presence of PVs leads to an increase in potential energy/atom. The current work provides an insight into adjusting the tensile mechanical behaviors by making vacancy defects in XN (X = Ga, In) and provides a guideline for the applications of XN (X = Ga, In) in flexible nanoelectronic and nanoelectromechanical devices.

Temperature and interlayer coupling induced thermal transport across graphene/2D-SiC van der Waals heterostructure.

Graphene based two-dimensional (2D) van der Waals (vdW) materials have attracted enormous attention because of their extraordinary physical properties. In this study, we explore the temperature and interlayer coupling induced thermal transport across the graphene/2D-SiC vdW interface using non-equilibrium molecular dynamics and transient pump probe methods. We find that the in-plane thermal conductivity κ deviates slightly from the 1/T law at high temperatures. A tunable κ is found with the variation of the interlayer coupling strength χ. The interlayer thermal resistance R across graphene/2D-SiC interface reaches 2.71 [Formula: see text] 10-7 [Formula: see text] at room temperature and χ = 1, and it reduces steadily with the elevation of system temperature and χ, demonstrating around 41% and 56% reduction with increasing temperature to 700 K and a χ of 25, respectively. We also elucidate the heat transport mechanism by estimating the in-plane and out-of-plane phonon modes. Higher phonon propagation possibility and Umklapp scattering across the interface at high temperatures and increased χ lead to the significant reduction of R. This work unveils the mechanism of heat transfer and interface thermal conductance engineering across the graphene/2D-SiC vdW heterostructure.

Identifying the Genetic Basis of Mineral Elements in Rice Grain Using Genome-Wide Association Mapping.

Mineral malnutrition is a major problem in many rice-consuming countries. It is essential to know the genetic mechanisms of accumulation of mineral elements in the rice grain to provide future solutions for this issue. This study was conducted to identify the genetic basis of six mineral elements (Cu, Fe, K, Mg, Mn, and Zn) by using three models for single-locus and six models for multi-locus analysis of a genome-wide association study (GWAS) using 174 diverse rice accessions and 6565 SNP markers. To declare a SNP as significant, -log10(P) ≥ 3.0 and 15% FDR significance cut-off values were used for single-locus models, while LOD ≥ 3.0 was used for multi-locus models. Using these criteria, 147 SNPs were detected by one or two GWAS methods at -log10(P) ≥ 3.0, 48 of which met the 15% FDR significance cut-off value. Single-locus models outperformed multi-locus models before applying multi-test correction, but once applied, multi-locus models performed better. While 14 (~29%) of the identified quantitative trait loci (QTLs) after multiple test correction co-located with previously reported genes/QTLs and marker associations, another 34 trait-associated SNPs were novel. After mining genes within 250 kb of the 48 significant SNP loci, in silico and gene enrichment analyses were conducted to predict their potential functions. These shortlisted genes with their functions could guide future experimental validation, helping us to understand the complex molecular mechanisms controlling rice grain mineral elements.

Atomistic reaction mechanism of CVD grown MoS2 through MoO3 and H2S precursors.

Chemical vapor deposition (CVD) through sulfidation of MoO3 is one of the most important synthesis techniques to obtain large-scale and high-quality two-dimensional (2D) MoS2. Recently, H2S precursor is being used in the CVD technique to synthesize 2D MoS2. Although several studies have been carried out to examine the mechanism of MoS2 growth in the presence of sulfur and MoO3 precursors, the growth of MoS2 in the presence of H2S precursor has largely remained unknown. In this study, we present a Reactive molecular dynamics (RMD) simulation to investigate the reaction mechanism of MoS2 from MoO3 and H2S precursors. The intermediate molecules formation, the reason behind those formations, and the surface compositions of MoOxSyHz during the initial steps of CVD have all been quantified. Surprisingly, a sudden separation of sulfur atoms from the surface was observed in the H2S precursor system due to the substantial oxygen evolution after 1660 K. The sulfur detachments and oxygen evolution from the surface were found to have a linear relationship. In addition, the intermediate molecules and surface bonds of MoS2 synthesized by MoO3 and H2S precursors were compared to those of a system using S2 and MoO3 precursors. The most stable subsidiary formation from the H2S precursor was found to be H2O, whereas in case of S2 precursor it was SO. These results provide a valuable insight in the formation of large-scale and high-quality 2D MoS2 by the CVD technique.

Vacancy-Induced Thermal Transport and Tensile Mechanical Behavior of Monolayer Honeycomb BeO.

Because of the rapid shrinking trend of integrated circuits, the performances of nanodevices and nanomechanical systems are greatly affected by the joule heating and mechanical failure dilemma. In addition, structural defects are inevitable during experimental synthesis of nanomaterials, which may alter their physical properties significantly. Investigation of the thermal transport and mechanical behavior of nanostructured materials with structural defects is thus a crucial requirement. In this study, the thermal conductivity (TC) and tensile mechanical behavior of monolayer honeycomb BeO are systematically explored using molecular dynamics simulations. An infinite length bulk TC of ∼277.77 ± 8.93 W/mK was found for the pristine monolayer BeO. However, the insertion of 1% single vacancy (SV) and double vacancy (DV) defects reduces the TC by ∼36.98 and ∼33.52%, respectively. On the other hand, the uniaxial tensile loading produces asymmetrical fracture stress, elastic modulus, and fracture strain behaviors in the armchair and zigzag directions. The elastic modulus was reduced by ∼4.7 and ∼6.6% for 1% SV defects along the armchair and zigzag directions, respectively, whereas the reduction was ∼2.7 and ∼ 5.1% for 1% DV defects. Moreover, because of the strong symmetry-breaking effect, both the TC and mechanical strength were significantly lower for the SV defects than those for the DV defects. The highly softening and decreasing trends of the phonon modes with increasing vacancy concentration and temperature, respectively, were noticed for both types of defects, resulting in a reduction of the TC of the defected structures. These findings will be helpful for the understanding of the heat transport and mechanical characteristics of monolayer BeO as well as provide guidance for the design and control of BeO-based nanoelectronic and nanoelectromechanical devices.

Community-based asthma assessment in young children: adaptations for a multicentre longitudinal study in South Asia.

Background: Systematic assessment of childhood asthma is challenging in low- and middle-income country (LMIC) settings due to the lack of standardised and validated methodologies. We describe the contextual challenges and adaptation strategies in the implementation of a community-based asthma assessment in four resource-constrained settings in Bangladesh, India, and Pakistan. Method: We followed a group of children of age 6-8 years for 12 months to record their respiratory health outcomes. The study participants were enrolled at four study sites of the 'Aetiology of Neonatal Infection in South Asia (ANISA)' study. We standardised the research methods for the sites, trained field staff for uniform data collection and provided a 'Child Card' to the caregiver to record the illness history of the participants. We visited the children on three different occasions to collect data on respiratory-related illnesses. The lung function of the children was assessed in the outreach clinics using portable spirometers before and after 6-minute exercise, and capillary blood was examined under light microscopes to determine eosinophil levels. Results: We enrolled 1512 children, 95.5% (1476/1512) of them completed the follow-up, and 81.5% (1232/1512) participants attended the lung function assessment tests. Pre- and post-exercise spirometry was performed successfully in 88.6% (1091/1232) and 85.7% (1056/1232) of children who attempted these tests. Limited access to health care services, shortage of skilled human resources, and cultural diversity were the main challenges in adopting uniform procedures across all sites. Designing the study implementation plan based on the local contexts and providing extensive training of the healthcare workers helped us to overcome these challenges. Conclusion: This study can be seen as a large-scale feasibility assessment of applying spirometry and exercise challenge tests in community settings of LMICs and provides confidence to build capacity to evaluate children's respiratory outcomes in future translational research studies.

Temperature- and Defect-Induced Uniaxial Tensile Mechanical Behaviors and the Fracture Mechanism of Two-Dimensional Silicon Germanide.

Recently, monolayer silicon germanide (SiGe), a newly explored buckled honeycomb configuration of silicon and germanium, is predicted to be a promising nanomaterial for next-generation nanoelectromechanical systems (NEMS) due to its intriguing electronic, optical, and piezoelectric properties. In the NEMS applications, the structure is subjected to uniaxial tensile mechanical loading, and the investigation of the mechanical behaviors is of fundamental importance to ensure structural stability. Here, we systematically explored the uniaxial tensile mechanical properties of 2D-SiGe through molecular dynamics simulations. The effects of temperature ranges from 300 to 1000 K and vacancy defects, for instance, point and bi vacancy, for both armchair and zigzag orientations of 2D-SiGe were investigated. In addition, the influence of system areas and strain rates on the stress-strain performance of 2D-SiGe has also been studied. With the increase in temperature and vacancy concentration, the mechanical properties of 2D-SiGe show decreasing behavior for both orientations and the armchair chirality shows superior mechanical strength to the zigzag direction due to its bonding characteristics. A phase transformation-induced second linearly elastic region was observed at large deformation strain, leading to an anomalous stress-strain behavior in the zigzag direction. At 300 K temperature, we obtained a fracture stress of ∼94.83 GPa and an elastic modulus of ∼388.7 GPa along the armchair direction, which are about ∼3.17 and ∼2.83% higher than the zigzag-oriented fracture strength and elastic modulus. Moreover, because of the strong regularity interruption effect, the point vacancy shows the largest decrease in fracture strength, elastic modulus, and fracture strain compared to the bi vacancy defects for both armchair and zigzag orientations. Area and strain rate investigations reveal that 2D-SiGe is less susceptible to the system area and strain rate. These findings provide a deep insight into controlling the tensile mechanical behavior of 2D-SiGe for its applications in next-generation NEMS and nanodevices.

Genetic Diversity and Population Structure Analysis of the USDA Olive Germplasm Using Genotyping-By-Sequencing (GBS).

Olives are one of the most important fruit and woody oil trees cultivated in many parts of the world. Olive oil is a critical component of the Mediterranean diet due to its importance in heart health. Olives are believed to have been brought to the United States from the Mediterranean countries in the 18th century. Despite the increase in demand and production areas, only a few selected olive varieties are grown in most traditional or new growing regions in the US. By understanding the genetic background, new sources of genetic diversity can be incorporated into the olive breeding programs to develop regionally adapted varieties for the US market. This study aimed to explore the genetic diversity and population structure of 90 olive accessions from the USDA repository along with six popular varieties using genotyping-by-sequencing (GBS)-generated SNP markers. After quality filtering, 54,075 SNP markers were retained for the genetic diversity analysis. The average gene diversity (GD) and polymorphic information content (PIC) values of the SNPs were 0.244 and 0.206, respectively, indicating a moderate genetic diversity for the US olive germplasm evaluated in this study. The structure analysis showed that the USDA collection was distributed across seven subpopulations; 63% of the accessions were grouped into an identifiable subpopulation. The phylogenetic and principal coordinate analysis (PCoA) showed that the subpopulations did not align with the geographical origins or climatic zones. An analysis of the molecular variance revealed that the major genetic variation sources were within populations. These findings provide critical information for future olive breeding programs to select genetically distant parents and facilitate future gene identification using genome-wide association studies (GWAS) or a marker-assisted selection (MAS) to develop varieties suited to production in the US.